1. Field of the Invention
The present invention relates to a heat exchanger tube block and to a multichamber flat tube that can be used for such a tube block.
2. Background of the Invention
A heat-exchanger tube block of the generic type is shown in the German patent document DE 39 36 106 A1. The tube block is built up from single-chamber flat tubes that are bent around in a U-shape once, or several times in meanders, by 180xc2x0 in the plane of their transverse and longitudinal extent and are stacked one above the other in the direction at right angles to these former directions, with the introduction of corrugated ribs between them. Depending on the number of flat-tube windings, the tube block therefore consists of two or more block units located one behind the other in the block depth (front to back) direction, each of which block units includes a stack of straight, flat-tube sections with parallel flow through them. Neighboring block units are in series fluid connection by means of the lateral U-bends in the flat tubes. The two ends of each flat tube open, on the same side of the block, into one associated collector duct extending along the block height direction, the two collector ducts being formed from one longitudinally divided collector box or two separated collector tubes.
The present invention concerns a tube block that includes a plurality of block units composed in each case of a plurality of tube units located one above the other in stack form, the stacking direction defining a block height direction and the flow ducts formed by the tube units extending in a block transverse direction at right angles to it. The block units are arranged one behind the other in the block depth (front to back) direction at right angles to the block height direction and the block transverse direction. The tube units emerge into collector ducts that are arranged so that they extend at the sides of the tube block in the block height direction, i.e. with the longitudinal centerline parallel to it. In the present case, the term xe2x80x9ccollector ductsxe2x80x9d is uniformly employed, for simplicity, for all ducts into which the tube units emerge, the concept involving collector ducts in the actual sense, in which the medium led in parallel through a plurality of tube units is collected for the purpose of removal from the tube block, and involving distributor ducts, in which the medium supplied to the tube block is distributed among a plurality of emerging tube units, and also involving reversal ducts in which the medium is deflected from a first group of emerging tube units into a second group of emerging tube units.
In use, a first medium flows through the tube block whereas a second medium, which has to be brought into thermal contact with the first medium, is channeled over the tube block in the block depth (front to back) direction with external flow onto the tube-block surfaces. Heat exchangers with such tube blocks are employed, for example, as evaporators and condensers in motor vehicle air-conditioning systems. The tube block is usually supplemented, in order to form a tube/rib block, by the introduction of heat-conducting corrugated ribs between the tube units. The tube units can, for example, be formed by flat tubes.
The present invention is based, as a technical problem, on the provision of a heat-exchanger tube block of the type described above, by means of which a heat exchanger with high heat transfer capability and a high level of pressure resistance is achieved with a relatively small filling quantity and with the possibility of variable guidance of the tempering medium led through it, and is based on a multichamber flat tube which is particularly suitable for the construction of such a tube block.
The invention solves this problem by providing a heat exchanger tube block and a multichamber flat tube with the following features.
In the heat exchanger tube block, at least one collector duct connection is provided between at least two neighboring block units, which collector duct connection connects one collector duct of one block unit directly to a collector duct of the other block unit. Here, the term xe2x80x9cdirectxe2x80x9d means that the relevant collector ducts are in connection by means of a corresponding fluid connection extending in the block depth (front to back) direction and not, or at least not only, by means of one or a plurality of the tube units of the block. By means of this one or preferably a plurality of direct fluid connections of the collector ducts arranged at the sides of the tube block, it is possible to realize a very variable flow guidance of the medium led through the system, for example a refrigerant of an air-conditioning system, which flow guidance is matched to the particular application. The plurality of block units which are located one behind the other in the block depth (front to back) direction and therefore in the flow direction of the other medium channeled over the tube block, makes it possible to achieve a high heat transfer capability for the tube block. The tube block can be built up from extruded flat tubes having ducts optimized with respect to low filling quantity, i.e. low volumes flowing through the tube block, and high pressure resistance. The collector ducts arranged at the sides of the tube block can be formed from highly pressure-resistant collector tubes of relatively small cross section, in particular where correspondingly narrow flat-tube units are used or where units of this type are used which have flat-tube ends rotated out of the transverse plane relative to the collector duct longitudinal direction.
In a tube block developed in accordance with the present invention, direct collector duct connections are provided between each pair of neighboring block units in such a way that the associated tempering medium flows through the block units in series.
In a tube block developed in accordance with the present invention, a collector space, which is formed for example by a collector tube or a collector box, is subdivided by transverse partitions into a plurality of collector ducts. This makes it possible to achieve a serpentine form of flow through a respective block unit deflected once or a plurality of times.
In a tube block developed in accordance with the present invention, the collector ducts on at least one side of the block are formed from individual collector tubes, respectively associated with a block unit, which collector tubes are at a distance apart in the block depth (front to back) direction, which, for example, facilitates the drainage of condensate water when used in an evaporator. The distance apart is produced by one or a plurality of distance elements, which are formed on the collector tubes or are attached to the latter.
In further embodiments, the distance element includes a shaped sheet-metal piece or tubular piece with at least one slot opening or includes an outwardly bulged passage on a collector tube. The distance elements configured in this way keep the collector tubes at a distance apart and simultaneously define a respective collector tube connection. In yet a further embodiment of the invention, the distance element can consist of two fluid-tight mutually abutting or mutually engaging passages, at least one of the two passages being bulged outward.
In a developed tube block in accordance with the present invention, the tube units are formed from straight flat-tube sections, which emerge with twisted tube ends into the collector tubes. Because of the twisting at the ends, the flat-tube ends are rotated out of the transverse plane of the collector tubes, which makes it possible to use collector tubes with an internal diameter smaller than the flat-tube width, so that the internal volume of the tube block can be kept small.
A tube block developed in accordance with the present invention is complemented by a tube/rib block. In this arrangement, a single corrugated rib can be introduced for each corrugated rib layer, the width of the corrugated rib corresponding essentially to the total block depth (front to back), or a plurality of corrugated ribs are provided adjacent to one another, it being possible for these to have the same or different width and structure.
In a tube block developed in accordance with the present invention, at least two tube units, located adjacent to one another in the block depth (front to back) direction, are realized as integral parts of a single-piece multichamber flat tube, the latter extending in the width over a corresponding number of block units.
The multichamber flat tube in accordance with the present invention is particularly suitable for building up the tube block just described. It is subdivided at the ends by one or a plurality of longitudinal slots into a plurality of separate end segments which are each twisted about its own longitudinal centerline. In the case of a tube block built up of such flat tubes, the end segments of each flat tube end region are then individually associated with the corresponding block units, so that the chambers of each flat tube are subdivided in groups among the corresponding block units, the respective chambers which emerge from one end segment being associated with one block unit.